1. Field of the Invention
This invention relates to a novel organic compound. More particularly it relates to a compound useful as a component of liquid crystal compositions and a liquid crystal composition containing the same.
2. Description of the Prior Art
Liquid crystal display devices have been used for various display devices, by utilizing the properties of the dielectric anisotropy, optical anisotropy, etc. in the liquid crystal phases of liquid crystal compounds and/or liquid crystal compositions. These displays are of liquid crystal display elements using the electro-optic effect of liquid crystals or those employing the thermo-optic effect and other optic effects, and a number of liquid crystal compounds have been used for liquid crystal display elements using the electric field effects such as twisted nematic effect, guest-host effect, etc., in cooperation with the advance of electronics. As to these liquid crystal materials, there is no single compound which satisfies all of the various characteristics of liquid crystal elements such as mesomorphic range, operating voltage, response properties, etc.; thus, several kinds of liquid crystal compounds and if necessary, non-crystal compounds have been blended and used for practical use.
Recently, the search for a liquid crystal display element capable of being driven in a higher temperature atmosphere and/or under lower voltages have been increasing, and a liquid crystal composition having a high transition point (clearing point) of liquid crystalline phase-isotropic liquid phase and/or a large dielectric anisotropy value has been desired.
The clearing point of liquid crystal composition has been known to be raised by adding a component having a high clearing point.
When liquid crystal compounds and/or liquid crystal compositions are filled in a cell provided with electrodes, and in most cases, in a cell provided with transparent and opposed electrodes, and liquid crystal display is controlled under voltages, the following has been observed:
One of factors having an effect upon the threshold voltage (V.sub.th) among voltages driving liquid crystal display cells is the dielectric anistropy value .DELTA..epsilon. (.DELTA..epsilon.=.epsilon..sub..parallel. -.epsilon..sub.195) of liquid crystal compounds and/or liquid crystal compositions, and increase in .DELTA..epsilon. has a tendency of reducing V.sub.th. When .DELTA..epsilon. is positive and large, it is possible to lower the driving voltage of cells provided with opposed electrodes having the same distance therebetween.
Some ester compounds having a pyrimidine ring have been known as liquid crystal compounds or a component of liquid crystal compositions or an intermediate thereof. As to compounds having a pyrimidine ring in the form of ##STR2## Zaschke et al disclose ##STR3## (wherein n=3-11) (Heterocyclic Liquid Crystals, Advanced Liquid Crystal Research and Applicants, Pargamon Press (1960), 1065). Further, Zaschke et al disclose ##STR4## wherein R represents C.sub.n H.sub.2n+1, C.sub.n H.sub.2n+1 O, C.sub.n H.sub.2n+1 OCOO, C.sub.n H.sub.2n+1 COO, C.sub.n H.sub.2n+1 S, F, Cl, Br, NO.sub.2, CN or CF.sub.3 and n represents 1 to 10 (U.S. Pat. No. 4,311,610).
Toki et al disclose ##STR5## (Japanese patent application laid-open No. Sho 56-164169/1981).
Schad et al disclose a composition containing ##STR6## on page 5Table II in GB 2092169, but it does not concretely describe the properties of compounds wherein a phenylpyrimidinecarboxylic acid derivative and a phenyl derivative are ester-linked.
As to these compounds, the benzene ring bonded directly to the pyrimidine ring has a carbonyl group or cyano group substituent, but the above references do not disclose any compounds wherein a pyrimidine ring bonded directly to a benzene ring has a carbonyl group substituent, whereas Boller et al disclose ##STR7## each as an intermediate of liquid crystal compounds (U.S. Pat. No. 4,062,798; Japanese patent publication No. Sho 55-27056 (1980)). However, this reference does not disclose an ester wherein the oxygen of the carboxyl group is bonded to a phenyl group.
Gray et al disclose a composition containing an ester of a 5-alkyl (or 5-alkoxy) pyrimidine-2-carboxylic acid with a 4-alkylphenol or 4-alkoxyphenol, ##STR8## wherein each R.sup.1 and R.sup.2 independently represents n-alkyl or n-alkoxy group having up to 12 carbon atoms.
And with regard to a reaction according to which a substituted-phenyl-2-(4-substituted-phenyl)-5-pyrimidine carboxylate or a substituted phenyl-5-(4-substituted phenyl)-2-pyrimidine carboxylate can be esterified, it states that methods of attachment of radicals R.sub.1 (A).sub.n to pyrimidine rings are known and such methods may be employed in the course of the formation of the appropriate esters or their precursors R.sub.1 (A).sub.n --BCO.OH and R.sub.1 (A).sub.1 --BOH (WO 86/00067, page 14, lines 17-20).
However, Gray et al do not disclose any compounds wherein a pyrimidine ring having a carbonyl group substituent is bonded directly to a benzene ring (page 18, Table 5).